The present invention relates to a method for the preparation of 1-aza-2-silacyclopentane compounds whose nitrogen is substituted by a hydrocarbon group or a heteroatom-containing hydrocarbon group. The method comprises effecting an intramolecular hydrosilylation reaction of a N,N-disubstituted aminosilane. In a preferred method the intramolecular hydrosilylation reaction is conducted in the presence of a rhodium-containing catalyst.
Among the 1-aza-2-silacyclopentane compounds known to date, 1-aza-2-silacyclopentane compounds having a carbon atom bonded at the 1 position (nitrogen atom) include 1,2,2-trimethyl -1-aza-2-silacyclopentane, 1-benzyl-2,2-dimethyl-1-aza -2-silacyclopentane, 1-phenyl-2,2-dimethyl-1-aza-2-silacyclopentane, 1,2,2,4-tetramethyl-1-aza-2-silacyclopentane, 1-(beta-aminoethyl)-2,2,3-trimethyl-1-aza-2-silacyclopentane, and so forth. The synthesis reactions of these compounds generally involve combinations of some number of equivalent reactions and are disadvantageous from an industrial perspective because of the problem of dealing with by-products as well as the number of steps in the production process.
For example, one method consists of the reaction of a (3-chloroalkyl)chlorosilane (e.g., ClCH.sub.2 CH.sub.2 CH.sub.2 SiR.sub.2 CL) ) with an excess of primary amine (J. L. Speier, C. A. Roth, J. W. Ryan, J. Org. Chem., Vol. 36, No. 21, 3121 (1971)). The drawbacks to this reaction are as follows: the starting (3-chloroalkyl)silanes are difficult to obtain in high yields, and the reaction produces 2 equivalents of ammonium salt as a by-product. Another method comprises the reaction of (3-chloroalkyl)hydrosilanes (e.g., ClCH.sub.2 CH.sub.2 CH.sub.2 SiR.sub.2 H) with an excess of primary amine (M. G. Voronkov, S. V. Kirpichenko, A. T. Abrosimova, A. I. Albanov, J. Organomet. Chem., 406, 87-9 (1991)). The problems with this reaction are that the starting (3-chloroalkyl)hydrosilanes are difficult to obtain and the reaction produces ammonium salt as a by-product.
The present invention makes possible the selective, high-yield preparation of 1-aza-2-silacyclopentane derivatives that have nonhydrolyzing functional groups on the N atom from the silyl derivatives of secondary allylamines, without generating ammonium salts as by-products.
The 1-aza-2-silacyclopentane derivatives of the present invention are useful as aminoalkyl-containing silane coupling agents that carry a hydrocarbyl group (e.g., allyl, phenyl, substituted phenyl, benzyl, substituted benzyl, and so forth) on the nitrogen atom, and are also useful as the corresponding end-stopping agents for polysiloxanes. Moreover, because of the high reactivity of the nitrogen-silicon bond, these derivatives can be used to synthesize a large number of organofunctional silane derivatives by ring-opening reactions and insertion reactions.